<template>
  <div class="pagination">
    <button :disabled='pageNo==1' @click="$emit('getPageNo',pageNo-1)">上一页</button>
    <button v-if="startNoAndEndNo.start>2" @click="$emit('getPageNo',1)" :class="{active:pageNo==1}">1</button>
    <button v-if="startNoAndEndNo.start>2">···</button>

    <button @click="$emit('getPageNo',page)" v-for="(page,index) in startNoAndEndNo.range" :key="index" :class="{active:pageNo==page}">{{page}}</button>
    
    <button v-if="startNoAndEndNo.end<totalPage-1">···</button>
    <button v-if="startNoAndEndNo.end<totalPage-1" @click="$emit('getPageNo',totalPage)" :class="{active:pageNo==totalPage}">{{totalPage}}</button>
    <button :disabled='pageNo==totalPage' @click="$emit('getPageNo',pageNo+1)">下一页</button>
    
    <button style="margin-left: 30px">共 {{total}} 条</button>
  </div>
</template>

<script>
  export default {
    name: "Pagination",
    props:["getPageNo","pageNo",'pageSize','total','continues'],
    computed: {
        totalPage(){
            // Math.ceil向上取整
            return Math.ceil(this.total/this.pageSize)
        },
        // 计算分页器起始页和结束页
        startNoAndEndNo(){
            var start=1,end=1;
            if(this.continues>this.totalPage){
                start=1;
                end=this.totalPage
            }
            else{
                start=this.pageNo-parseInt(this.continues/2)
                end=this.pageNo+parseInt(this.continues/2)
                if(start<1){
                    start=1
                    end=this.continues
                }
                if(end>this.totalPage){
                    end=this.totalPage
                    start=this.totalPage-this.continues+1
                }
            }
            let range=[],i;
            for(i=start;i<=end;i++)
            range.push(i)
            return {range,start,end}
        }
    }
  }
</script>

<style lang="less" scoped>
  .pagination {
      text-align: center;
    button {
      margin: 0 5px;
      background-color: #f4f4f5;
      color: #606266;
      outline: none;
      border-radius: 2px;
      padding: 0 4px;
      vertical-align: top;
      display: inline-block;
      font-size: 13px;
      min-width: 35.5px;
      height: 28px;
      line-height: 28px;
      cursor: pointer;
      box-sizing: border-box;
      text-align: center;
      border: 0;

      &[disabled] {
        color: #c0c4cc;
        cursor: not-allowed;
      }

      &.active {
        cursor: not-allowed;
        background-color: #409eff;
        color: #fff;
      }
    }
  }
  .active{
    background-color: skyblue;
  }
</style>
